What is a cyst?
A cyst is a lump under the skin. It can grow on any part of your body and is full of air, fluid, or pus. Pilar cysts affect the scalp while epidermoid, or sebaceous cysts, appear on the face, upper body, and neck. Other types of cysts include ganglion cysts, which usually form on the hands, wrists and fingers, and Baker’s cysts which form on the back of the knee and are fluid-filled.
Most cysts are harmless and grow slowly but they can, in some cases, become infected. You’re more likely to have a cyst if you’re female, middle-aged, you have acne, if there’s a family history of cysts, or if you have Gardner syndrome.